THE GENUS CHORDEILES SWAINSON OBERHOLSEK. 101 



and sides of neck blackish brown, much mingled with white and 

 biiffy ; a large triangular patch on throat white ; below this a band of 

 dark brown, much spotted with ochraceous buff; breast dark brown, 

 finely mottled and vermiculated with whitish; lower breast cream 

 white, with conspicuous dark brown cross-bars; abdomen, sides, 

 flanks, and crissum, ochraceous buff, with conspicuous dark brown 

 cross-bars, these narrower, farther apart, and somewhat broken on 

 lower tail-coverts; lining of wing deep ochraceous buff, barred with 

 dark brown. 



Iris dark brown; bill brownish; feet dull brownish. 



Measurements. — Male: Total length (in flesh), 200 mm.^ 



Male: 2 Wing, 161.5-176 (average, 169.4) mm.; tail, 92.5-102.5 

 (99.1) ; exposed culmen, 5.0-6.2 (5.7) ; tarsus, 12.5-13.8 (13.3) ; mid- 

 dle toe, 14-14.7 (14.4). 



Female: 2 Wing, 158.5-168 (162.1) mm.; tail, 90-98.5 (94.4); ex- 

 posed culmen, 5.0-6.5 (5.8) ; tarsus, 12-14 (13.1) ; middle toe, 13-15.3 

 (14.1). 



Type-locality. — Xbac, Yucatan, Mexico. 



Geographical distrihution. — Central America and southern Mexico. 

 Breeds in the Lower Tropical, Upper Tropical, and Lower Austral 

 zones of Guatemala, British Honduras, Yucatan, and other parts 

 of southern Mexico: north to Eio Lagartos, and Merida, Yucatan; 

 Campeche, Campeche; Montecristo, Tabasco; Pelenque, Chiapas; 

 and San Mateo, Oaxaca ; northwest along the Pacific slope of IMexico 

 to Colima; Zapotlan and Atemajac (near Guadalajara), Jalisco; 

 south to Tuxtla Gutierrez, and San Bartolome, Chiapas ; and Coban, 

 Guatemala; east to British Honduras; and Mujeres Island, eastern 

 Yucatan. In migration southeast through Honduras, Nicaragua, and 

 Costa Rica, to Gatun, in the Canal Zone, Panama. Winters in Pan- 

 ama and Costa Rica, possibly also in other and more northwestern 

 parts of Central America. Not known from South America. 



Remarks. — This form differs from Chordeiles acutipennis exiUs 

 in larger size; rather darker lower parts, the white interspaces on 

 posterior portion being narrower; somewhat darker, more brownish 

 general effect of the upper surface; and in darker, more ochraceous 

 or buffy (less whitish) light bars on the under side of the tail. 



Specimens from Costa Rica and Nicaragua and one from Panama 

 (Gatun, Canal Zone, No. 207668, U.S.N.M.) appear to be exactly 

 the same as those from Yucatan and Chiapas, and are doubtless 

 immigrants, as there seems to be no breeding record of this species 

 for Panama, Costa Rica, Nicaragua, Honduras, or Salvador. 



1 One specimen. 



2 Seven specimens, from Yucatan, Mexico. 



